Improvement in furnace-doors



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METERS, PHOTD-LITMOGRAPHER. WASHINGTON, D. C.

UNITED STATES PATENT OFFICE.

JOHN WIGKERSHAM, OF BALTIMORE, MARYLAND.

IMPROVEMENT IN FURNACE-DOORS.

Specification forming part of Letters Patent No. 51,638, dated December19, D565.

of introducing air through a large number of Y small orifices orperforations made in lsaid door above the fuel-bed of a furnace or otherheater, so that the columns or jets of air entering and passing throughsaid orifices may mix lnore readily with the gases arising from thefuel,

' serving better to burn such gases, economize fuel, and aid inproducing a better blast.

The universal and rapidly-increasing use of steam as a motive power hasled to many experiments whereby to economize fuel in generating thesame, and while some success has been obtained, it has been but partialand insufficient, as also attended with more or less complications andexpense. Perfect combustion and the economy of fuel has also beendesirable in other heaters not generating steam. To accomplish theseresults or ends my invention has been made.

In the drawings, Figure 1 represents an elevation of the furnace-door ofa locomotive or boiler with my invention applied, and Fig. 2 is acentral section through the same.

A represents the frame of the door; B B, the hinges 5 C, the latch; D,aplate perforated with a series of small orifices, a a, through whichthe air enters; E is a slide-door behind this plate, to regulate thequantity of air to pass in. It is self-evident that the air suppliedthrough these orifices a a will enter the furnace above the fuel-bed asa series of small columns or jets of air, and will mingle moreintimatelyand readily with the gaseous products, assisting in a more rapid andcomplete combustion of the said gases, as well as of the fuel itself.This feeding of air, too, acts as a blower, giving a better blast. Theseresults have been fully established by experiment. The action of thesejets of air (entering the furnace as a shower, exposing so much moresurface than if supplied in any other way) maybe com pared to a seriesofblow-pipe blasts, insuring a higher temperature, a more perfectchemical action, and consequently a more perfect combustion, for thesegases, without a properly regulated quantity of air, and that properlysupplied or fed, will pass off unconsumed and wasted into the flue orchimney. In entering the furnace these small currents or jets of coldair have a tendency to fall down upon the mass of fuel, (arising fromthe difference in their specific gravity and that of the heated airwithin,) and, meeting the ascending currents of heated gases, as theyarise from vthe same fuel, the more speedy and perfect min glin gisfacilitated. The temperature of these small currents is somewhatmodified by friction in passing through the orifices or perforations.

lf necessary, the slide-door may be put in front of the perforatedplate, andinclin'ed slats may be put on the inside to deiiect thecurrents of air more directly down upon the fuelbed. If a thicknon-combustible substance be used in the door the orifices may be boredwith an inclination downward on theinside. These modifications andothers may be made without eifecting the nature of my invention, andthese series of small orifices may be made or placed elsewhere, ifdesired, than in the furnace-door.

Some of the results obtained by experiment by supplying air in thismanner over the fuelbed of a locomotive-furnace are thefollowingviz:that bituminous coal reduced to a. fine dust yields as good a fire asthe lump coal; that it is not drawn through the iiuesv to the sameextent, (less by three-fourthsp that the particles lodged in thesmoke-box are much smaller in size; that by opening the exhaust, whichchange is shown to be admissible and advisable always when possible, thesmokebox may be rendered nearly, if not quite, entirely free from coke;that the smoke-stack throws but little smoke or coke, except while thefire-door is open and fresh fuel is being added, and hence there is muchless liability of re therefrom, and that the front of the smoke -box isnot liable to be burned out. Again, the coal passes over the period ofcoking without crusting upon the top, and the use of the poker is butseldom required. A continuous blaze is kept up over the entire coal-bed,which is notburned in strips or holes, as is otherwise generally thecase. That when the proper quantity of air is found it shows that inrising an inclined plane, there being more steam used and exhausted inthe smokestack, the steam gage always indicates an increase of steam inthe boiler at that time, which usually necessitates the opening of thesmoke-box door, so as to counteract the effects of the exhaust.

It has been shown by experiment on a stationary engine that a moreregular head of steam, with a saving of nearly twenty-tive per cent.offuel and with a reduction of nearly one-half of thelaborof thcfireman,is obtained; also, that an inferior quality of coal can be used,which otherwise could not-be. Screenings from anthracite orsemi-bituminous coal, (usually termed lime-burnerscoal,) being` thelowestpriced coal sold in our markets, when mixed with one-half or lessCumberland, yielded the same fire as when Cumberland alone was used.

I have found that orifices about one-sixteenth by one thirtysecon d area goed size for ordinary purposes; but the diameters may bevaried-increased or decreased-if found desirable, under varyingcircumstances.

lhe principle of my invention is equally applicable to all kinds offurnaces, stoves, or heaters for burning fuel, and is especiallyapplicable in the burning of anthracite coal, so as to produce anabundant blaze. Any of the usual devices may be employed to regulate theamount of air to be introduced. This method of feeding air is a greatprotection to the door if perfbrated, preventing, in a great measure,its burning` out. Plate-iron about one-eighth inch thick, for locomotivepurposes, will be a sufficient thickness.

I am aware that air has been introduced into the rebox of locomotives,stationary furnaces, &c., in various waysfrom underneath, from the sidesand front, through tubes, hollow stay-bolts, or other large-sized holes.

I am aware that double perforated doors have been used; also, iu a fewinstances, single ones,having a few largesized holes at the bottom and aperforated slide connected therewith; but all these devices have failedto secure anything like, or even approaching, a maximum amount ofcombustion, and most have been condemned upon trial as inefficient andexpensive in mechanical construction, as also wasteful of heat and fuel.They differ from my invention in the means, and more particularl y, inthe result to be obtained, which, in my case, is secured by a large gainof chemical force, brought about by supplying the air in the manner Itiothrough a door resembling a fine sieve.

'In the double doors which have been used (intended to restrain the airand raise its temperature) volume and velocity are both sacriiiced, aswell as chemical force, blast, &c.,this owing to the few large holes infront plate, as, also many large ones comparatively in inside plate.

In the rare instances of single doors with a few large holes-say, one,two, or three-and a perforated slide, chemical force-one of the mostimportant results gained by my invention-is lost. In such doors it willbe found the slide so operates as to aifect each .hole alike, opens orcloses, or partially opens or closes, each and every one, so that thegreater necessity for air in the furnace the wider they depart from theprinciple of chemical force or aflinity, and by lowering the temperatureof the furnace it causes effects diametrically opposite to thoseintended, and which ought to follow. With my slide Iclose or obliterateentirely just such a number of holes as I desire, leaving the restentirelyopen, in order to secure the necessary quantity or supply of air(at the same time I preserve the blast or velocity) and the chemicalforce arising from a multiplicity of minute currents of air falling uponthe lire-bed and mixing with gaseous products. f

My invention is both blast and mixture, and may be used on both sides offuel-door, so as to cover the whole of the fire-bed, insuring moreperfect com busticn than has hitherto been attained.

Having thus described my invention, what I claim as new, and desire tosecure by 4Letters Patent of the United States, is-

The combination and arrangement of the blank-slide A and perforated doorB, whereby to regulate the supply of air over a tire-bed withoutaffecting the velocity or blast, at saine time preserving the molecularcurrents, which secure a large gain of chemical force.

' JNO. WICKERSHAM.

Witnesses S. S. FAHNEs'rooK, A. EBERT.

